Re: [PATCH v2 1/1] pgo: Fix allocate_node() v2

Kees Cook
2021-06-03T21:37:56Z

On Thu, Jun 03, 2021 at 02:14:24PM -0700, Nathan Chancellor wrote:
> On 6/3/2021 6:38 AM, Jarmo Tiitto wrote:
> > Based on Kees and others feedback here is v2 patch
> > that clarifies why the current checks in allocate_node()
> > are flawed. I did fair amount of KGDB time on it.
> >
> > When clang instrumentation eventually calls allocate_node()
> > the struct llvm_prf_data *p argument tells us from what section
> > we should reserve the vnode: It either points into vmlinux's
> > core __llvm_prf_data section or some loaded module's
> > __llvm_prf_data section.
> >
> > But since we don't have access to corresponding
> > __llvm_prf_vnds section(s) for any module, the function
> > should return just NULL and ignore any profiling attempts
> > from modules for now.
> >
> > Signed-off-by: Jarmo Tiitto <jarmo.tiitto@gmail.com>
>
> I agree with Nick on the comments about the commit message. A few more small
> nits below, not sure they necessitate a v3, up to you. Thank you for the
> patch!

It would make my life easier to get a v3. :) I agree with all of
Nathan's suggestions. :)

Thanks!

-Kees

--
Kees Cook